Crime Scene Search Methods

The Crime Scene is search for the physical evidences (visible or invisible). There are various types of search methods employed by the investigating officers and the forensic scientists at the scene of crime. The searching methods mainly depends on:

• Type of Crime (Rape, murder, burglary, theft, etc.)

• Nature of Crime (Homicide, suicide, or accident)

• Size of the crime scene (macroscopic or microscopic)

• Location of the crime scene (indoor, outdoor, combination of indoor or outdoor, or any remote area like underwater, desert, etc.)

• Complexity of the crime scene 

Before deciding the search method, all the investigators and the forensic experts must follow the general guidelines (check list) to observe the crime scene after due recording:

1. Are the doors and windows locked or unlocked? Open or shut? 

2. Are there signs of forced entry, such as tool marks or broken locks?

3. Is the house or the crime scene is in good order? If not, does it look like there was a struggle or was the victim just messy?

4. Is there mail/post/suicidal note/threatening note/ etc. lying around? Has it been opened? Or where it is located?

5. Is the kitchen in good order? Is there any partially eaten food? Is the table set? If so, for how many people?

6. Are there signs of a party, such as empty glasses or bottles or full ashtrays?

7. If there are full ashtrays, what brands of cigarettes are present? 

8. Is there anything that seems out of place? Is there a couch blocking a doorway?

9. Is there trash in the trash cans? Is there anything out of the ordinary in the trash? Is the trash in the right chronological order? If not, someone might have been looking for something in the victim's trash.

10.  Are the bathroom towels wet? Are the bathroom towels missing? Are there any signs of a cleanup?

11. If the crime is a shooting, how many shots were fired? The CSI will try to locate the gun, each bullet, each shell casing and each bullet hole.

12. If the crime is a stabbing, is a knife obviously missing from victim's kitchen? If so, the crime may not have been premeditated.

13. Are there any shoe prints or any other footwear marks on the floor or in the area immediately outside the building?

14. Are there any tire marks in the driveway or in the area around the building?

15. Is there any blood splatter on floors, walls or ceilings?

Irrespective of the type of crime scene, the investigator has to decide the appropriate method immediately, without delay, so as to collect the evidences in the intact form as far as possible. Following are the basic search methods, usually commissioned on the crime scene:

1. Zonal Method

2. Strip Method

3. Line Search

4. Grid Method

5. Spiral Method (Outward Spiral & Inward Spiral)

6. Wheel Search Method

7. Random Search

   Zonal Method: In this method the crime scene is virtually divided into different zones. The number of zones depends upon the size and complexity of the crime scene. This method can be applicable to both indoor and outdoor crime scenes. Different people will be employed in individual zones, and will search their zones thoroughly for the evidences normally as well as using different techniques (UV/IR/Video). After searching in their own zones, the zones will be exchanged to check the accuracy and double check for any missing items. This method cannot be applicable on very squeezed and complex crime scenes like elevators, lift shafts, or stairs.

   Strip or Parallel Method: In this method the virtual strips or line are being imagined to walk through on the crime scene and look for the evidences. The method is well suited for the crime scene like class rooms, where rows are present already, each row can be considered as a strip. Also, minimum number of the personals are required for this method. One person will start the walk through from one corner of the strip and will move towards the other looking for the evidences. The walk through should be slow and thorough. If two personals are employed, then each of them can start from two different points and continuing to the different ends to double check the search.

   Grid Method (two parallel strip): It is just like the strip method; the only difference is that two strips are considered to form a grid. Again, only two people can do the searching walking through on separate strips and then will switch their strips for the more accuracy. It is a good method for large indoors and outdoors crime scenes.

   Spiral Method: This is well suited for lager indoor and outdoor crime scene with less obstacles (like furniture etc.). The searcher will start either from the center of the room (outward) or from the periphery (inward) search as show in the images below. Also, two investigators can search together, one moving from the center towards the periphery and other one vice versa.

   Wheel Search Method: This method is only applicable to the lager outdoor scenes like fields, desert, or other such open areas. It is like the zonal method; however, the wheel is divided into various zones depending upon the size of the crime scene. Different individuals will be employed in separate zones and then switching their zone for more accuracy. The investigators or the searchers can begin from the epicenter moving towards their zones to complete the search, and then returning back to the epicenter for the discussion or collection procedures.

  Random Search Method: This is the most common method employed by the investigators, because of the feasibility at any location. No above-mentioned ruled to be followed for this method. It is also advisable to consider this method on complex crime scenes.

Levels of Searches:

First Level: search at the scene of crime

Second Level: through photographs, sketches, witnesses, relatives, and other sources

Third Level: Revisit the crime scene if possible, Interrogation etc.

Evidence Removal:

The investigator or the forensic expert has to be sure to document each and every evidence encountered at the particular scene. The evidences should only be removed after proper documentation (photography/videography/sketching/notes), and then should be properly collected in appropriate containers.